1. Field of the Invention
The present invention is directed to a remote control for a combined ceiling fan and light fixture. Specifically, the present invention is directed to a remote control which may be used as a replacement for an existing wall switch and provide for control of the ceiling fan and accompanying light fixture without any modification to the existing electrical wiring between the wall switch and the light fixture.
2. Description of the Prior Art
Ceiling fans known in the prior art provide for a variety of desired features. Specifically, modem ceiling fans may be controlled to operate at a plurality of different speeds from a relatively low speed to a high maximum speed. Low speeds may be desirable to provide for general air circulation and to eliminate "hot" or "cold" spots within a room. Higher speeds may be desirable for cooling effects (in summer) or to eliminate temperature gradients (in winter). In addition, the direction of rotation may generally be controlled to be in either one of two opposite directions. In the winter, it is generally desirable to have the fan turn in one direction to circulate hot air away from the ceiling. In the summer, it may be desirable to have the fan turn in the opposite direction to provide a cooling effect on the occupants in the room.
Ceiling fans are often combined with a light fixture or fixtures with the intensity level of the light fixture(s) controlled from low levels to maximum high levels. Most ceiling fans are designed so that they may be installed in existing ceiling junction boxes, replacing existing light fixtures. In such an installation, shown in FIG. 1, there is generally a wall switch 101 switching load line 102 from A.C. supply voltage 170 in the house. Switched load line 103 and neutral line 104 from A.C. supply voltage 170 terminate in a ceiling junction box 105. A ceiling fan 120 comprising fan 106 with light fixture 180 is typically installed attached to junction box 105 in a similar manner as a standard light fixture. Because ceiling fan 120 must be adaptable to existing wiring in the house, fan speed switch 107, fan direction switch 108, and light intensity switch 109 are usually mounted on a housing attached to ceiling fan 120 itself.
Fan mounted switches 107, 108, and 109 may be preset to the desired levels of speed, direction, and light intensity, respectively, and wail switch 101 used to turn fan 106 and light fixture 180 to these preset levels. The disadvantage of such an approach is that each time the user wishes to change the existing levels, a switch must be changed at ceiling fan 120. For example, during the daytime, it may be desirable to run fan 106 at a high speed and shut off light fixture 180 in order to cool the house. In the evening, it may be desirable to run fan 106 at a medium speed and turn light fixture 180 on to maintain an even temperature throughout the house and to provide illumination, respectively. At night, it may be desirable to run fan 106 at low speed and turn light fixture 180 off to maintain air circulation with a minimum of noise. If ceiling fan 120 is located at a sufficient distance above the floor, it may be necessary to use a step stool or ladder in order to reach fan mounted switches 107, 108, and 109 in order to change the speed or direction of fan 106 or the intensity of light fixture 180. Alternately, long pull chains may be attached to fan mounted switches 107, 108 and 109 to allow the user to reach the switches. Such long pull chains are not aesthetically pleasing, however, and suffer the additional disadvantage of lowering clearance for taller occupants. Further, the plurality of pull chains are difficult to distinguish from one another (e.g., light vrs. speed vrs. direction). Finally, pull chains can be very difficult to operate, especially with regard to speed control, as the fan has a certain amount of inertia, making it difficult for the user to immediately determine whether the proper speed has been selected.
One way to overcome the disadvantages of the installation of FIG. 1 would be to install separate circuits to individual wall mounted switches for the fan speed and lighting control as shown in FIG. 1.A. In FIG. 1.A., the wall switch 101 of FIG. 1 has been replaced by a separate light switch 101a and fan switch 101b. Load line 103 of FIG. 1 has been replaced with light load line 103a and fan load line 103b. In the installation of FIG. 1.A., both the fan and light fixture can be turned on or off from the wall mounted switches 101a and 101b. While such an installation may be practical in new construction, in an existing home it would be necessary to remove portions of the ceiling and walls to run the additional wiring. In addition, in either new or existing construction, running additional wires involves additional expense and in some localities may require the services of a licensed electrician. Further, many ceiling fans are sold as owner-installed units with an easy to use installation kit. The complexities of house wiring are beyond the capabilities of most "do-it-yourselfers" and the length of wiring in each installation would be different, adding expense to the installation kit. Finally, despite the high cost of the installation shown in FIG. 1.A., the device provides for only a simple on-off control of both the fan 106 and light fixture 180. Remote fan speed, light intensity, and fan direction control cannot be provided in the installation shown in FIG. 1.A. unless extra components are installed with switches 101a and 101b.
One prior art device which has been used to provide a partial solution to the above described problem of remotely controlling the operation of ceiling fan is shown in U.S. Pat. No. 4,413,211 issued Nov. 1, 1983 to Fowler. This prior an Patent is directed towards a remote load selector which uses an existing wall switch to control a load by toggling the existing switch to provide for the selective application of power to multiple loads such as a combined ceiling fan and light fixture. The Fowler '211 device has a number of limitations due to the fact that the user must apply power by manually toggling the wall switch. For instance, the user may become confused as to which level the fan was previously switched to, making control difficult. In addition, the prior art load selector described above is generally limited in the number of control steps that can be realistically accomplished by the application and removal of power to the loads. For example, a typical ceiling fan may have three speeds in two separate directions, making a total of six different combinations of toggled signals that may be sent. If a light fixture is added to the fan, the number of combinations may be doubled to twelve. If the light fixture has more than one intensity setting, or if additional fan speeds are desired, the number of toggled combinations expands geometrically. The user may find himself toggling the wall switch repeatedly trying to find the proper combination of light intensity, fan speed, and fan direction.
A further prior art device which provides a partial solution to the above described problem of remotely controlling the operation of ceiling fan is disclosed in Fowler U.S. Pat. No. 4,465,956, issued Aug. 14, 1984. FIGS. 2 and 2.A. show a simplified schematic and waveforms of the Fowler '956 invention. Fowler '956 discloses a technique for controlling a ceiling fan and light fixture using a technique known as the diode method. In the Fowler '956 device, wall switch 101 of FIG. 1 is replaced with wall mounted remote control 211 containing light switch 201a, fan switch 201b, diode D1 and diode D2. In the diode method, A.C. supply voltage 270 to fan mounted control unit 210 is momentarily rectified by wall mounted remote control 211. The rectified wave in one direction is treated as one signal while the rectified wave in the other direction is treated as another signal.
In normal operation, as shown in FIG. 2, both light switch 201a and fan switch 201b are closed, and no diode is in the circuit. Light switch 201a and fan switch 201b are both momentary contact spring release type switches which are normally closed (NC). In normal operation, the load current passing from load line 202 to switched load line 203 passes through switches 201a and 201b, bypassing diodes D1 and D2 and producing a normal AC waveform 222 (FIG. 2.A.) on switched load line 203.
When fan switch 201b is pressed, diode D2 is switched into the circuit, momentarily rectifying A.C. supply voltage 270 to the positive half of the A.C. waveform as shown by waveform 223 in FIG. 2.A. Fan mounted control unit 210 detects positive rectified waveform 223 and treats it as a fan control signal. Fan mounted control unit 210 may either alter fan speed or direction, or turn fan 206 on or off. Typically, fan mounted control unit 210 will control the fan so that each successive fan control signal received will cycle the fan through a predetermined control pattern (e.g., low, medium, high, off).
Similarly, by pressing light control switch 201a, diode D2 will be placed in the circuit and the A.C. supply voltage 270 will be momentarily rectified in the negative direction to produce waveform 224 as shown in FIG. 2.A. Fan mounted control 210 will interpret waveform 224 as a light control signal and control light fixture 230 accordingly (e.g., low, medium, high, off).
The Fowler '956 device of FIG. 2 will provide an effective wall mounted remote control for a ceiling fan using existing wiring, however, the apparatus does suffer from some drawbacks. For example, momentary interruptions in the A.C. supply voltage 270 caused by the power company could be interpreted by fan mounted control 210 as command signals, erroneously switching fan 206 or light fixture 230 on or off. Such erroneous switching would be undesirable, for example, at night when it is desired to leave light fixture 230 off. Similarly, when a home is not occupied, if a momentary interruption in A.C. supply voltage 270 occurs, fan 206 or light 230 may switch on, wasting energy.
Another prior art device which attempts to provide a partial solution to the above described problem of remotely controlling a ceiling fan is disclosed in Hart U.S. Pat. No. 4,719,446, issued Jan. 12, 1988. FIGS. 3 and 3.A. show a simplified schematic and waveform, respectively, of the Hart '446 invention. Hart discloses a technique for controlling a ceiling fan and light fixture using a technique known as the phase control method. In the Hart device, wall switch 101 of FIG. 1 is replaced with a wall mounted remote control 311 containing light switch 301a, fan switch 301b, diode D3, diode D4, resistor R1, capacitor C1 and triac Q1. In the phase control method, pan of normal waveform 322 (FIG. 3.A.) of A.C. supply voltage 370 to fan mounted control unit 310 is momentarily interrupted by wall mounted remote control 311. If the interruption is in the positive side of the waveform, as shown in waveform 323 in FIG. 3.A., it is treated as one signal. If the interruption is on the negative side, as shown in waveform 324 in FIG. 3.A., it is treated as another signal. In normal operation, as shown in FIG. 3, both light switch 301a and fan switch 301b are closed, and no diode is in the circuit. Light switch 301a and fan switch 301b are both momentary contact spring release type switches which are normally closed (NC). In normal operation, the load current passing from load line 302 to switched load line 303 passes through switches 301a and 301b, bypassing diodes D3 and D4 and triac Q1 producing a normal AC waveform 322 on switched load line 303.
When fan switch 301b is pressed, diode D4 is switched into the circuit, blocking the positive half of the waveform of A.C. supply voltage 370. Resistor R1 and capacitor C1 form an RC timing network to delay the firing of triac Q1 such that the positive half of the waveform of A.C. supply voltage 370 is delayed by a preset amount producing waveform 323 as shown in FIG. 3.A. Fan mounted control unit 310 detects this delay and treats it as a fan control signal. Fan mounted control unit 310 my either alter fan speed or direction, or turn fan 306 on or off. Typically, Fan mounted Control unit 310 will control the fan so that each successive fan successive control signal will cycle the fan through a predetermined control pattern (e.g., low, medium, high, off).
Similarly, by pressing light control switch 301a, diode D3 will be placed in the circuit, blocking the negative portion of the waveform of the A.C. supply voltage 370 and allowing triac Q1 to delay the negative portion of the waveform of the A.C. supply voltage 370 by a predetermined amount to produce waveform 324 as shown in FIG. 3.A. Fan mounted control 310 will interpret this signal as a light control signal and control light fixture 330 accordingly (e.g., low, medium, high, off).
The Hart device of FIG. 3 will provide an effective wall mounted remote control for a ceiling fan using existing wiring, however, the apparatus does suffer from some drawbacks. For example, momentary interruptions in the A.C. supply voltage 370 or noise spikes caused by switching inductive loads (e.g., electric motors) could be interpreted by fan mounted control 310 as command signals, erroneously switching fan 306 or light fixture 330 on or off. Further, the Hart device of FIG. 3, like the Fowler device of FIG. 2, can only provide for two signal levels (e.g., fan and light) on the A.C. waveform. If a further number of signals are desired, a more sophisticated receiving and transmitting circuit would have to be constructed.
One apparatus which attempts to overcome the deficiencies of both the Hart and Fowler devices is that shown Fowler U.S. Pat. No. 4,439,576. FIGS. 4 and 4.A. shows a simplified schematic and waveform, respectively, of the Fowler '576 invention. Fowler discloses a technique for controlling a ceiling and light fixture using a technique known as the proportional voltage drop method. In the Fowler '576 device, wall switch 101 of FIG. 1 is replaced with a wall mounted remote control 411 containing light switch 401a, fan switch 401b, resistor R1 and resistor R2. Further switches and resistors may be employed to provide additional levels of control, however, for the sake of illustration, the apparatus is shown here with two switches and two resistors.
In the proportional voltage drop method, part of normal waveform 422 (FIG. 4.A.) of the A.C. supply voltage 470 having peak voltage V1 (typically 170 volts for a 120 V.A.C. system) is transmitted to fan mounted control unit 410 over control line 403a and is proportionally dropped from its peak voltage by wall mounted remote control 411. If the voltage drop is at a first level V2 as shown in waveform 423 in FIG. 4.A., it is treated as one signal. If the voltage drop is at a second level V3 as shown in waveform 424 in FIG. 4.A., waveform 424 is treated as another signal. In normal operation, as shown in FIG. 4, both light switch 401a and fan switch 401b are open, and no resistor is in the circuit. Light switch 401a and fan switch 401b are both momentary contact spring release type switches which are normally open (NO). In normal operation, the load current passes from load line 402 to fan mounted control unit 410, bypassing switches 401a and 401b, to produce a normal AC waveform 422 on load line 402 and no output on control line 403a.
When fan switch 401b is pressed, resistor R2 is switched into the circuit, from the A.C. supply voltage 470, producing a proportional voltage drop on control line 403a shown as waveform 423 as shown in FIG. 4.A. Fan mounted control unit 410 compares this voltage to the A.C. supply voltage 470 from load line 402 and treats it as a fan control signal. Fan mounted control unit 410 my either alter fan speed or direction, or turn fan 406 on or off. Typically, Fan mounted Control unit 410 will control the fan so that each successive fan successive control signal will cycle the fan through a predetermined control pattern (e.g., low, medium, high, off).
Similarly, by pressing light control switch 401a, resistor R1 will be placed in the circuit, producing a different proportional voltage drop of the A.C. supply voltage 470 on control line 403a shown as waveform 424 as shown in FIG. 4.A. Fan mounted control 410 will interpret this signal as a light control signal and control light fixture 430 accordingly (e.g., low, medium, high, off).
In the Fowler '576 invention, if the resistors are selected for a 120 V line voltage and the supply voltage changes, say to 110 V, the control signals will change proportionally. Without additional circuitry to sense the change in supply voltage, the new signal may not represent the correct control signal and may trigger the load incorrectly. Fowler attempts to minimize the effect of variations in line voltage by utilizing unregulated voltage to pre-bias the sensing network.
In order to pre-bias the sensing network, however, the Fowler '576 invention requires the use of three wires as input to the fan mounted control. Thus, the two wires at an existing wall switch would require rewiring, and these two wires would no longer be in series with load. As discussed above, one of the critical criteria for a remote control for a ceiling fan is that it be installed using existing wiring. In addition, since the proportional voltage drops in the Fowler '576 device are produced by resistive devices, the amount of voltage drop will be proportional to the current passing through the resistors. If more current passes through the resistors, the voltage drop will increase proportionally, possibly causing a loss of control.
Further, in the Fowler '576 device, the power to the appliance does not pass through the remote control per se, as the remote control is wired in parallel with the appliance rather than in series with the appliance. Thus, the remote control is not provided with any means of shutting off all power to the appliance (i.e., main cutoff switch). Such a power cutoff is desirable in order to satisfy electrical codes as well as to provide the user with a positive means for turning off all power to the appliance. In order to provide a power cutoff switch to the Fowler '576 device, load line 402 would have to be run through the remote control and an additional load rated switch installed.
In view of the deficiencies of the above prior art devices, it remains a requirement in the art to provide an inexpensive remote control for a ceiling fan which can be easily installed using existing wiring, and provide for easy to use and reliable control of fan speed and light intensity.